Dear EarthTalk:

I hear that world population just topped eight billion. Is this growth wreaking havoc on the environment/climate and what is the prognosis for population growth globally over next few decades?

Peter. W., Albuquerque, NM

Global population has indeed reached eight billion, but it won’t remain there for long. Lower mortality rates and longer life expectancies have contributed to elevated population numbers. Although richer countries have lowered their birth rates in recent decades, poorer countries—specifically those in sub-Saharan Africa—continue to have high birth rates. Whether or not we will be able to support a continually growing population is still a hotly debated topic.

Many analysts still subscribe to philosopher Thomas Malthus’ hypothesis, first postulated in a 1798 essay, that humans’ ability to provide more and more resources will always be overwhelmed by ever-increasing population growth numbers. But others believe that growing population numbers can be supported with proper and effective resource allocation. Regardless, a growing population coupled with climate change will have an impact on resource availability and distribution.

Population projections are inherently tricky. It’s impossible to account for every scenario that could be a determinant over the course of a century. The Department of Economic and Social Affairs of the United Nations Secretariat (UNPD) projects that human population will pass 10 billion by 2100. However, a convergence of population forecasts created by the Wittgenstein Centre projected a global population of 8.79 billion by 2100 after an initial peak of 9.73 billion in 2064. This projection is vastly lower than UNPD’s projections due to their different modeling approaches.

The Wittgenstein Centre’s models arrived at different population totals based on variables such as fertility, mortality and migration pattern changes. The models predicted a lower total fertility rate (TFR) as access to education and contraception for childbearing people increased. A low TFR will have long term impacts on the overall global population. A reduced global population would reduce carbon dioxide output and lower resource needs and stresses, but climate change will continue to have consequences that will affect resource availability for decades to come even if we are successful at reining in emissions.

Social programs and systems will need to adapt as populations age and access to contraception and education increases. Age gaps will expand in countries with low TFRs. Labor forces will decrease, social security and universal healthcare systems will become strained and economic growth will be lowered as a result. These factors create a daunting task to support a growing global population, but it is possible.

Global population numbers do put a large strain on the environment, so it is important to elect policymakers who support a sustainable future with commitments to reduce fossil fuel emissions and who uphold and encourage reproductive education and healthcare for everyone, especially childbearing people. Whether our future will be some sort of Malthusian hell or a global garden where most of us receive the nourishment and resources needed to survive is still anybody’s guess.

CONTACTS

• The Global Population Will Soon Reach 8 Billion—Then What?, un.org/en/un-chronicle/global-population-will-soon-reach-8-billion-then-what
• Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100, thelancet.com/journals/lancet/article/PIIS0140-6736(20)30677-2/fulltext#seccestitle10.